Fuel inside oil cap?
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Posting Guru
Joined: Aug 2001
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Fuel inside oil cap?
The other day I went to change my Bronco's oil, and I noticed that inside the oil cap there was a milky yellow residue, that at first I thought was coolant. My 302 has been running fine,no white smoke when accelerating, so I don't think it's a head gasket. I took a rag and cleaned out the inside of the cap,and smelled it.It smells like gasoline.So I changed the oil,and cleaned out the oil breather cap.Today when I checked the oil level,I didn't see any of that yellowish residue,but the inside of the cap had brown stuff in it,that almost looked like mud. Another thing I've noticed is that on really cool mornings,the vehicle smells like fuel. Checked the gastank, and no leaks. The truck is running fine,no loss in power, no hesitation,but oil isn't supposed to smell like fuel.
Postmaster
Joined: Aug 2001
Posts: 2,882
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From: Nevada
Fuel inside oil cap?
Just a thought,
I'm not familiar with newer Broncos, but pre-EFI pieces had the crankcase ventilation from the valve cover into the carb. A faulty PCV valve will allow gas vapors (which solidify) to be sucked into the crankcase by that vacuum.
I'm not familiar with newer Broncos, but pre-EFI pieces had the crankcase ventilation from the valve cover into the carb. A faulty PCV valve will allow gas vapors (which solidify) to be sucked into the crankcase by that vacuum.
Senior User
Joined: Jan 2003
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From: Memphis, TN
Fuel inside oil cap?
george
Gasoline vapors don't solidify - at least not at any temperature you're likely to drive in. If they did, your gas tank & vapor line would be packed before it left the dealer's lot.
DG
Sounds like you have some blowby or a ruptured fuel pressure regulator (if it's EFI). A compression test never hurts, and can tell a lot about an engine's condition.
Gasoline vapors don't solidify - at least not at any temperature you're likely to drive in. If they did, your gas tank & vapor line would be packed before it left the dealer's lot.
DG
Sounds like you have some blowby or a ruptured fuel pressure regulator (if it's EFI). A compression test never hurts, and can tell a lot about an engine's condition.
Postmaster
Joined: Aug 2001
Posts: 2,882
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From: Nevada
Fuel inside oil cap?
My error - I'm no chemist, but was under the impression that gasoline hydrocarbons, when combined with oxygen, produced oxidation or gum, usually brown in color, which smells like and is soluable by gasoline. I live in a desert where high temperatures create a gum and moisture problem in long-term storage of gasoline (one year is long-term here) in simply vented containers such as lawn mower, pressure washer, generator and older auto/truck gas tanks and their induction systems. I've noticed that blowby from worn rings and faulty PCV systems produce what looks like that same gunk in breather caps that I see in ventilated gas tank caps.
